As much as possible, avoid accessing the Pylons template context c
(or tmpl_context). c is a thread-global variable, which
encourages spaghetti code that’s difficult to understand and to debug.

Instead, have controller methods add variables to the extra_vars
parameter of render(), or have the templates
call
template helper functions instead.

extra_vars has the advantage that it allows templates, which are
difficult to debug, to be simpler and shifts logic into the easier-to-test and
easier-to-debug Python code. On the other hand, template helper functions are
easier to reuse as they’re available to all templates and they avoid
inconsistencies between the namespaces of templates that are rendered by
different controllers (e.g. one controller method passes the package dict as an
extra var named package, another controller method passes the same thing
but calls it pkg, a third calls it pkg_dict).

Always use url_for() (available to templates as
h.url_for()) when linking to other CKAN pages, instead of hardcoding URLs
like <ahref="/dataset">. Links created with
url_for() will update themselves if the URL routing
changes in a new version of CKAN, or if a plugin changes the URL routing.

A JavaScript module should have a docstring at the top of the file, briefly
documentating what the module does and what options it takes. For example:

"use strict";/* example_theme_popover * * This JavaScript module adds a Bootstrap popover with some extra info about a * dataset to the HTML element that the module is applied to. Users can click * on the HTML element to show the popover. * * title - the title of the dataset * license - the title of the dataset's copyright license * num_resources - the number of resources that the dataset has. * */ckan.module('example_theme_popover',function($){return{initialize:function(){// Access some options passed to this JavaScript module by the calling// template.varnum_resources=this.options.num_resources;varlicense=this.options.license;// Format a simple string with the number of resources and the license,// e.g. "3 resources, Open Data Commons Attribution License".varcontent='NUM resources, LICENSE'.replace('NUM',this.options.num_resources).replace('LICENSE',this.options.license)// Add a Bootstrap popover to the HTML element (this.el) that this// JavaScript module was initialized on.this.el.popover({title:this.options.title,content:content,placement:'left'});}};});

Any JavaScript module that calls this.sandbox.client.subscribe()
should have a teardown() function that calls
unsubscribe(), to prevent memory leaks.
CKAN calls the teardown() functions of modules when those modules are
removed from the page.

There shouldn’t be very many cases where a JavaScript module really needs to
use Pubsub, try to only use it when you really need to.

JavaScript modules in CKAN are designed to be small and loosely-coupled,
for example modules don’t share any global variables and don’t call
each other’s functions. But pubsub offers a way to tightly couple JavaScript
modules together, by making modules depend on multiple events published by
other modules. This can make the code buggy and difficult to understand.

Always use CKAN’s custom {%snippet%} tag instead of Jinja’s default
{%include%} tag. Snippets can only access certain global variables, and
any variables explicitly passed to them by the calling template. They don’t
have access to the full context of the calling template, as included files do.
This makes snippets more reusable, and much easier to debug.

A snippet should have a docstring comment at the top of the file that briefly
documents what the snippet does and what parameters it requires. For example:

{#Renders a list of the site's most popular groups.groups - the list of groups to render#}<h3>Most popular groups</h3><ul>{%forgroupingroups%} <li> <a href="{{h.url_for('group_read',action='read',id=group.name)}}"> <h3>{{group.display_name}}</h3> </a>{%ifgroup.description%} <p>{{h.markdown_extract(group.description,extract_length=80)}} </p>{%else%} <p>{{_('This group has no description')}}</p>{%endif%}{%ifgroup.package_count%} <strong>{{ungettext('{num} Dataset','{num} Datasets',group.package_count).format(num=group.package_count)}}</strong>{%else%} <span>{{_('0 Datasets')}}</span>{%endif%} </li>{%endfor%}</ul>